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Nat Mater. 2018 Jan;17(1):63-71. doi: 10.1038/nmat5021. Epub 2017 Oct 30.

Additively manufactured hierarchical stainless steels with high strength and ductility.

Author information

1
Materials Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
2
Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
3
Materials Engineering Division, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
4
Division of Materials Sciences and Engineering, Ames Laboratory (USDOE), Ames, Iowa 50011, USA.
5
School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, Oregon 97331, USA.

Abstract

Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength-ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications.

PMID:
29115290
DOI:
10.1038/nmat5021

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